The present study was aimed to assess the effectiveness of individual psychotherapy undertaken at the Psychological Clinic of the Universidad de La Frontera (Temuco, Chile) and its relationship with the therapeutic alliance. The investigation involved 23 adult patients with neurotic symptoms. Their therapeutic processes were carried out by 11 trainee students from the regular psychology training program. Out of these, 4 therapists were performing their first supervised psychotherapeutic experience, and 7 therapists were undertaking their professional training using either a psychodynamic or a humanistic- experiential approach. The therapeutic processes considered in this study lasted between 5 and 42 sessions, comprising the following closure modalities: agreed closure between the patient and therapist because of the fulfillment of objectives, closure requested by the patient, and withdrawal of the therapeutic process. The instruments used were the Outcome Questionnaire (OQ-45.2) adapted for Chilean population by De la Parra and Von Bergen (2000, 2002), an instrument that allows to evaluate the level of change in the final course of the therapy and its outcomes; and the Working Alliance Inventory (Inventario de Alianza Terapéutica, IAT-P) adapted for Chilean population by Santibánez (2001), an instrument that evaluates the level of therapeutic alliance from the perspective of the patient. The study was quantitative in nature, with a unique group design and evaluations at the beginning and at the end of the therapy. For each patient, the OQ-45.2 was administered at the end of the first, and after the last psychotherapy session. In addition, the IAT-P was administered once, at the fourth session. In order to assess the pre-post psychotherapy differences, a samples-related t test was performed. In addition, a Reliable Change Index was calculated using scores of the first and final OQ-45.2 administration; and finally, the percentage of patients with clinically significant change, was estimated. The administration of the IAT-P showed a restriction of range with positive bias both, on overall total scale scores as well on each subscale score. For this reason, using the median, two subgroups for the overall IAT were created. Also, two subgroups were generated for each subscale: a subgroup of subjects with scores higher than the median and a subgroup of subjects with scores below the median. Then, by using the Mann-Whitney U test, the Reliable Change Index from the groups with high or low levels of alliance were compared. Results of this study showed significant differences between the first and last application of the OQ-45.2. In order to estimate whether the change was clinically significant, cut-off scores and Reliable Change Index were used. In the OQ-45.2 scale, 17 patients left the clinical group, 12 people met the Reliable Change Index criterion, and 8 people showed a clinically significant change. In relation to the closure modality, 7 patients with clinically significant change ended the psychotherapy with a discharge given by the therapist, while one requested the closure of the therapy. Scores from the IAT-P were located in the upper two thirds of the scale. The Bond Subscale had the highest mean, while Tasks and Goals got a slightly lower value. With respect to the main issue, it was found a significant association between therapeutic alliance and the outcome of the psychotherapy both, on overall total scale scores of the OQ-45.2 as well Symptoms Scale of the same instrument. Results showed that the alliance between therapist and the patient especially helped to reduce patient's symptoms. In addition, it was evident that students in training were able to establish good alliance with their patients, and thus to promote the achievement of the therapeutic outcome. These results are discussed taking into account current research on this topic.